1. Field of the Invention
The present invention relates to an electronic device that has a substrate mounted with an electronic circuit and accommodated in a housing and to a metal plate member employed in the electronic device.
2. Description of the Related Art
Recently, various types of mobile personal computers (abbreviated as PC hereinafter) have come into widespread use. One such a PC is a so-called notebook PC composed of a main unit incorporating an arithmetic circuit and having a keyboard on the front surface thereof and a display unit having a display screen and being capable of folded onto the main unit. Another type of such a PC is a pure-tablet (slate) PC that incorporates an arithmetic circuit and has a display screen on the top surface thereof, to which a keyboard is optionally externally connected.
Such mobile PCs are made thinner to reduce the overall size and weight while maintaining the required display screen size. For further reduction in size and weight, a metal housing is often employed, which is also useful to provide an electromagnetic shield between the inside and the outside of the housing.
Additionally, a cable or the like used for connection to another device compromises the mobility of such mobile PCs, so that many mobile PCs incorporate radio communication features conforming to various standards, such as the wireless LAN and the Bluetooth (registered trademark). When a mobile PC incorporates radio communication features, it needs a reliable electromagnetic shield and a countermeasure for suppressing noise due to radio wave generated by an internal circuit.
For example, in Japanese Patent Laid-Open No. 2005-75301, there is proposed the device housed in a metal casing and having shot-range radio communication functions such as the Bluetooth that suppresses radio wave noise without compromising performance of transmitting and receiving radio waves.
Meanwhile, conventional measures against noise have needed certain space in a device for suppressing noise, which is becoming difficult due to the latest demand for a thinner and lighter device.